In recent years, in the field of optical communication or optical measurement, optical waveguide devices such as waveguide-type optical modulators in which optical waveguides are formed on a substrate having an electro-optic effect and a control electrode for controlling light waves that propagate through the optical waveguides is formed are frequently used.
The control electrode in the above-described optical waveguide device has a structure in which a signal electrode is disposed so as to be put between ground electrodes, and, regarding the shape thereof, a variety of inventions have been proposed (for example, refer to Patent Literature 1 and 2).